Description
What package does this bug report belong to?
webview_flutter [All versions including latest version)
What target platforms are you seeing this bug on?
iOS [ Physical Device instead of Simulator]
Have you already upgraded your packages?
Yes
Dependency versions
name: webviewbug
description: "A new Flutter project."
publish_to: 'none' # Remove this line if you wish to publish to pub.dev
version: 1.0.0+1
environment:
sdk: ^3.8.1
dependencies:
flutter:
sdk: flutter
webview_flutter: ^4.13.0
pubspec.lock
# Generated by pub
# See https://dart.dev/tools/pub/glossary#lockfile
packages:
async:
dependency: transitive
description:
name: async
sha256: "758e6d74e971c3e5aceb4110bfd6698efc7f501675bcfe0c775459a8140750eb"
url: "https://pub.dev"
source: hosted
version: "2.13.0"
boolean_selector:
dependency: transitive
description:
name: boolean_selector
sha256: "8aab1771e1243a5063b8b0ff68042d67334e3feab9e95b9490f9a6ebf73b42ea"
url: "https://pub.dev"
source: hosted
version: "2.1.2"
characters:
dependency: transitive
description:
name: characters
sha256: f71061c654a3380576a52b451dd5532377954cf9dbd272a78fc8479606670803
url: "https://pub.dev"
source: hosted
version: "1.4.0"
clock:
dependency: transitive
description:
name: clock
sha256: fddb70d9b5277016c77a80201021d40a2247104d9f4aa7bab7157b7e3f05b84b
url: "https://pub.dev"
source: hosted
version: "1.1.2"
collection:
dependency: transitive
description:
name: collection
sha256: "2f5709ae4d3d59dd8f7cd309b4e023046b57d8a6c82130785d2b0e5868084e76"
url: "https://pub.dev"
source: hosted
version: "1.19.1"
cupertino_icons:
dependency: "direct main"
description:
name: cupertino_icons
sha256: ba631d1c7f7bef6b729a622b7b752645a2d076dba9976925b8f25725a30e1ee6
url: "https://pub.dev"
source: hosted
version: "1.0.8"
fake_async:
dependency: transitive
description:
name: fake_async
sha256: "5368f224a74523e8d2e7399ea1638b37aecfca824a3cc4dfdf77bf1fa905ac44"
url: "https://pub.dev"
source: hosted
version: "1.3.3"
flutter:
dependency: "direct main"
description: flutter
source: sdk
version: "0.0.0"
flutter_lints:
dependency: "direct dev"
description:
name: flutter_lints
sha256: "5398f14efa795ffb7a33e9b6a08798b26a180edac4ad7db3f231e40f82ce11e1"
url: "https://pub.dev"
source: hosted
version: "5.0.0"
flutter_test:
dependency: "direct dev"
description: flutter
source: sdk
version: "0.0.0"
leak_tracker:
dependency: transitive
description:
name: leak_tracker
sha256: "6bb818ecbdffe216e81182c2f0714a2e62b593f4a4f13098713ff1685dfb6ab0"
url: "https://pub.dev"
source: hosted
version: "10.0.9"
leak_tracker_flutter_testing:
dependency: transitive
description:
name: leak_tracker_flutter_testing
sha256: f8b613e7e6a13ec79cfdc0e97638fddb3ab848452eff057653abd3edba760573
url: "https://pub.dev"
source: hosted
version: "3.0.9"
leak_tracker_testing:
dependency: transitive
description:
name: leak_tracker_testing
sha256: "6ba465d5d76e67ddf503e1161d1f4a6bc42306f9d66ca1e8f079a47290fb06d3"
url: "https://pub.dev"
source: hosted
version: "3.0.1"
lints:
dependency: transitive
description:
name: lints
sha256: c35bb79562d980e9a453fc715854e1ed39e24e7d0297a880ef54e17f9874a9d7
url: "https://pub.dev"
source: hosted
version: "5.1.1"
matcher:
dependency: transitive
description:
name: matcher
sha256: dc58c723c3c24bf8d3e2d3ad3f2f9d7bd9cf43ec6feaa64181775e60190153f2
url: "https://pub.dev"
source: hosted
version: "0.12.17"
material_color_utilities:
dependency: transitive
description:
name: material_color_utilities
sha256: f7142bb1154231d7ea5f96bc7bde4bda2a0945d2806bb11670e30b850d56bdec
url: "https://pub.dev"
source: hosted
version: "0.11.1"
meta:
dependency: transitive
description:
name: meta
sha256: e3641ec5d63ebf0d9b41bd43201a66e3fc79a65db5f61fc181f04cd27aab950c
url: "https://pub.dev"
source: hosted
version: "1.16.0"
path:
dependency: transitive
description:
name: path
sha256: "75cca69d1490965be98c73ceaea117e8a04dd21217b37b292c9ddbec0d955bc5"
url: "https://pub.dev"
source: hosted
version: "1.9.1"
plugin_platform_interface:
dependency: transitive
description:
name: plugin_platform_interface
sha256: "4820fbfdb9478b1ebae27888254d445073732dae3d6ea81f0b7e06d5dedc3f02"
url: "https://pub.dev"
source: hosted
version: "2.1.8"
sky_engine:
dependency: transitive
description: flutter
source: sdk
version: "0.0.0"
source_span:
dependency: transitive
description:
name: source_span
sha256: "254ee5351d6cb365c859e20ee823c3bb479bf4a293c22d17a9f1bf144ce86f7c"
url: "https://pub.dev"
source: hosted
version: "1.10.1"
stack_trace:
dependency: transitive
description:
name: stack_trace
sha256: "8b27215b45d22309b5cddda1aa2b19bdfec9df0e765f2de506401c071d38d1b1"
url: "https://pub.dev"
source: hosted
version: "1.12.1"
stream_channel:
dependency: transitive
description:
name: stream_channel
sha256: "969e04c80b8bcdf826f8f16579c7b14d780458bd97f56d107d3950fdbeef059d"
url: "https://pub.dev"
source: hosted
version: "2.1.4"
string_scanner:
dependency: transitive
description:
name: string_scanner
sha256: "921cd31725b72fe181906c6a94d987c78e3b98c2e205b397ea399d4054872b43"
url: "https://pub.dev"
source: hosted
version: "1.4.1"
term_glyph:
dependency: transitive
description:
name: term_glyph
sha256: "7f554798625ea768a7518313e58f83891c7f5024f88e46e7182a4558850a4b8e"
url: "https://pub.dev"
source: hosted
version: "1.2.2"
test_api:
dependency: transitive
description:
name: test_api
sha256: fb31f383e2ee25fbbfe06b40fe21e1e458d14080e3c67e7ba0acfde4df4e0bbd
url: "https://pub.dev"
source: hosted
version: "0.7.4"
vector_math:
dependency: transitive
description:
name: vector_math
sha256: "80b3257d1492ce4d091729e3a67a60407d227c27241d6927be0130c98e741803"
url: "https://pub.dev"
source: hosted
version: "2.1.4"
vm_service:
dependency: transitive
description:
name: vm_service
sha256: ddfa8d30d89985b96407efce8acbdd124701f96741f2d981ca860662f1c0dc02
url: "https://pub.dev"
source: hosted
version: "15.0.0"
webview_flutter:
dependency: "direct main"
description:
name: webview_flutter
sha256: c3e4fe614b1c814950ad07186007eff2f2e5dd2935eba7b9a9a1af8e5885f1ba
url: "https://pub.dev"
source: hosted
version: "4.13.0"
webview_flutter_android:
dependency: transitive
description:
name: webview_flutter_android
sha256: f6e6afef6e234801da77170f7a1847ded8450778caf2fe13979d140484be3678
url: "https://pub.dev"
source: hosted
version: "4.7.0"
webview_flutter_platform_interface:
dependency: transitive
description:
name: webview_flutter_platform_interface
sha256: f0dc2dc3a2b1e3a6abdd6801b9355ebfeb3b8f6cde6b9dc7c9235909c4a1f147
url: "https://pub.dev"
source: hosted
version: "2.13.1"
webview_flutter_wkwebview:
dependency: transitive
description:
name: webview_flutter_wkwebview
sha256: a3d461fe3467014e05f3ac4962e5fdde2a4bf44c561cb53e9ae5c586600fdbc3
url: "https://pub.dev"
source: hosted
version: "3.22.0"
sdks:
dart: ">=3.8.1 <4.0.0"
flutter: ">=3.27.0"
Steps to reproduce
We use addJavaScriptChannel
to communicate between JS and flutter. And the whole flutter app is likely to crash in iOS native side when there are messages sent from javascript side.

A minimal reproducible code is attached at code sample part. In the reproducible code, I created a loop to send JS channel messages every 5 milliseconds.
<script>
let i = 0;
function showToast() {
Toaster.postMessage('Hello! ' + i++);
setTimeout(showToast, 5);
}
showToast();
</script>
You can launch the app. Then press Hot Reload button in Flutter IDE. Repeat Hot Reload multiple times, then the issue will happen.
I guess the root cause is because, when we reload a flutter app, flutter disposes the corresponding webview controller. However, the native webview page is not disposed. And when there is a JS message, then the swift code crashes.
Expected results
The app does not crash when hot reload.
Actual results
The app occasionally crashes when hot reload.
Code sample
Code sample
import 'package:flutter/material.dart';
import 'package:webview_flutter/webview_flutter.dart';
void main() => runApp(const MaterialApp(home: WebViewExample()));
const String kLocalExamplePage = '''
<!DOCTYPE html>
<html lang="en">
<head>
<title>Load file or HTML string example</title>
</head>
<body>
<h1>Local demo page</h1>
<p>
This is an example page used to demonstrate how to load a local file or HTML
string using the <a href="https://pub.dev/packages/webview_flutter">Flutter
webview</a> plugin.
</p>
<script>
let i = 0;
function showToast() {
Toaster.postMessage('Hello! ' + i++);
setTimeout(showToast, 5);
}
showToast();
</script>
</body>
</html>
''';
class WebViewExample extends StatefulWidget {
const WebViewExample({super.key});
@override
State<WebViewExample> createState() => _WebViewExampleState();
}
class _WebViewExampleState extends State<WebViewExample> {
late final WebViewController controller;
@override
void initState() {
super.initState();
controller = WebViewController()
..setJavaScriptMode(JavaScriptMode.unrestricted)
..addJavaScriptChannel(
'Toaster',
onMessageReceived: (JavaScriptMessage message) {
ScaffoldMessenger.of(context).showSnackBar(SnackBar(content: Text(message.message)));
},
)
..loadHtmlString(kLocalExamplePage);
}
@override
Widget build(BuildContext context) {
return Scaffold(
appBar: AppBar(title: const Text('Flutter WebView example')),
body: WebViewWidget(controller: controller),
);
}
}
Screenshots or Videos
Screenshots / Video demonstration
[Upload media here]
Logs
Logs
Runner(84730,0x20bde0100) malloc: xzm: failed to initialize deferred reclamation buffer [2] (null)
flutter: The Dart VM service is listening on http://127.0.0.1:49607/HVNG-1oMLUk=/
webview_flutter_wkwebview/ProxyAPIRegistrar.swift:73: Fatal error: webview_flutter_wkwebview.PigeonError: Error returned from calling WKScriptMessageHandler.didReceiveScriptMessage: Optional("Unable to establish connection on channel: \'dev.flutter.pigeon.webview_flutter_wkwebview.WKScriptMessageHandler.didReceiveScriptMessage\'.")
Flutter Doctor output
Doctor output
Doctor summary (to see all details, run flutter doctor -v):
[✓] Flutter (Channel stable, 3.32.3, on macOS 15.4.1 24E263 darwin-arm64, locale
en-US)
[✓] Android toolchain - develop for Android devices (Android SDK version 35.0.1)
[✓] Xcode - develop for iOS and macOS (Xcode 16.3)
[✓] Chrome - develop for the web
[✓] Android Studio (version 2024.3)
[✓] VS Code (version 1.101.0)
[✓] VS Code (version 1.99.1)
[✓] Connected device (4 available)
! Error: Browsing on the local area network for iMeng. Ensure the device is unlocked and attached with a cable or associated with the same local area network as this Mac.
The device must be opted into Developer Mode to connect wirelessly. (code -27)
[✓] Network resources
• No issues found!